Method and apparatus for making filter rods



May 22, 1962 R. o. WHITEHEAD ET AL 3,

METHOD AND APPARATUS FOR MAKING FILTER RODS Filed Dec. 19, 1958 may/#20MA47066 RAYMOND 0. W/l/TE/S'EAD JOSE/q! MAST/FR INVENTORS United StatesPatent 3,035,497 METHOD AND APPARATUS FOR MAKING FILTER RODS Raymond 0.Whitehead, New Brunswick, Joseph Master,

Highland Park, and Richard Marogg, New Brunswick,

N.J., assignors to Kimberly-Clark Corporation, Neenah,

Wis., a corporation of Delaware Filed Dec. 19, 1958, Ser. No. 781,622 4Claims. (Cl. 93-1) This invention relates to the manufacture of filtersof the type especially adapted for use in so-called filter tipcigarettes, and has particular reference to a method and apparatus formaking a filter rod consisting essentially of a compacted rod-like massof fibrous filtering material.

It is a general object of the invention to provide certain improvementsin the apparatus and procedural steps described and illustrated in US.Patent No. 2,849,932, issued September 2, 19-58.

The invention relates to the known type of procedure in which a Web offibrous material such as paper or its equivalent is drawn from acontinuous supply, then converged or gathered to form' a relativelycompact rod-like strand or bundle adapted to be enclosed within awrapper strip. The resultant continuous filter rod may be cut intoselected lengths, and individual short lengths are ultimatelyincorporated with the cigarette by the cigarette manufacturer, or usedin similar fashion in cigarette holders or the like.

In accordance with the procedure described in said earlier patent, No.2,849,932, the web of fibrous material is subjected to mutilation priorto its formation into the rod-like condition. The mutilation is of akind which lacerates the web without destroying the continuity of theweb, thereby separating and exposing additional fibers of the web. It isan object of the present invention to pro vide improvements in thisprocedure, and in an apparatus for carrying it out, whereby enhancedfiber separation and exposure can be achieved, and with greateruniformity, economy, and reliability when the invention is practiced ona commercial scale.

More specifically, the improvements in the apparatus involve a moreefiicient means for lacerating or mutilating the continuous web offibrous material as it is drawn from a supply; and another improvementrelates to a new and unusually eifecive device for initiating theconvergence of the mutililated Web toward the compacted rod-likeformation. The improvements in the basic procedure reside in thepreliminary formation of transverse crinkles or crepes in the web offibrous material and the subsequent subjection of the web tolongitudinally extending corrugations in combination with irregulartears along closely spaced longitudinal lines. The combined effect oftransverse deformations in the web at the start, and longitudinaldistortions and lacerations superimposed thereon, has proven to beunusually desirable in achieving the purposes of the invention.

The preferred mode of attaining these objectives, and such other obejctsas may hereinafter appear or be pointed out, is exemplified in theaccompanying drawings in which- FIG. 1 is a diagrammatic perspectiveview of the procedure and apparatus in the region to which the presentinvention relates;

FIG. 2 is an elevational view of one of the mutilating or embossingrollers shown in FIG. 1;

FIG. 3 is a greatly enlarged fragmentary view of the nested mutilatingrollers, with the web of material passing between them;

FIG. 4 is a fragmentary face view of the fibrous web prior to itssubjection to the action of the mutiliating rollers;

FIG. 5 is a greatly enlarged schematic cross-sectional view in thedirection 5-5 of FIG. 4;

FIG. 6 is a fragmentary face view of the fibrous web after passingbetween the mutilating rollers;

FIG. 7 is a greatly enlarged schematic cross-sectional view in thedirection '7-7 of FIG. 6; and

FIG. 8 is a perspective view of a piece of the resultant filter rod.

The filtering material is preferably, but not necessarily, composed ofrelatively thin cellulosic tissue of fibrous nature having goodfiltering characteristics. It is easily tearable in a manner to spreador separate its fibers, and it has a softness which permits it to bereadily compressed or compacted into rod-like formation withoutdestruction of its porosity. While the terms web and paper are both usedherein, the intent in each case is to refer to any fibrous material insheet form having the tearability, porosity, and other characteristicsalluded to.

The procedure involves the advancement of a web 10 of this material froman appropriate supply to and between a pair of mutilatiug or embossingrollers 11 which are mounted for rotation on parallel adjacent axes. Themutilated web (indicated by the reference numeral 12.) is caused to passaround a special guide roller 13 which directs the web through a sharpchange of direction and initiates the convergence of the web, asindicated at 14, toward a compacted rod-like formation. The compressedand compacted web is appropriately tensioned (by a means not shown inFIG. 1) and is enclosed within a. wrapper 15 preferably composed ofpaper (see FIG. 8). A continuous length of this filter rod emanates fromthe output end of the apparatus, and is cut off into desired lengths bya suitable knife or other cutting instrumentality. Subsequently thefilter rod is cut into relatively shorter lengths for incorporation intocigarettes or cigarette holders.

The apparatus for carrying out this procedure is preferably of thegeneral character shown in the aforementioned Patent No. 2,849,932, andincludes a means for delicately adjusting the mutiliating rollers 11toward and away from each other, so that the spacing between them may bevaried to a fine degree.

One of the features of the present invention resides in the novelconfiguration and co-action of the rollers 11. As best indicated inFIGS. 2 and 3, these rollers have each the same circumferentiallygrooved configuration defining closely spaced alternate ridges andvalleys. The invention is not restricted to any specific set ofdimensions, but in order that the nature and functioning of theapparatus may be better understood, it may be stated that valleys spacedapart by 0.05 inch (center to center), having a depth of 0.04 inch and awidth of the order of 0.035 inch, have proven to be satisfactory for thepurpose. Each of the rollers may have a diameter of approximately 3inches, and a length dependent upon the width of the web undertreatment. A length of approximately 20 inches is usually sufiicient.

A special feature of the new surface configuration resides in providingeach ridge with a cross-sectional contour which exposes at least onesharp edge, and imparting to each valley a cross-sectional contour whichpresents a relatively fiat surface in opposition to each ridge edge whenthe rollers are arranged in nested proximity with the ridges of eachroller extending into the valleys of the other. The preferred way ofachieving this objective is shown in FIGS. 2 and 3, in which it will benoted that each of the ridges 16 has a fiat outer face 17, bounded bysharp lateral edges 18. Each of the valleys 19 has a smoothly curvedconcave cross-sectional contour. It will be apparent from aconsideration of FIG. 3 that each valley thus presents a relatively fiatsurface in opposition to each ridge edge 18 of the other roller.

Because of the arrangement of the rollers 11 in nested proximity, theweb 18 that is caused to pass between them is stretched and distortedinto a longitudinally corrugated state. It is squeezed to a maximumdegree along the parallel longitudinal regions which pass over the sharpcorners or edges 18. By adjusting the proximity of the rollers, thedegree of this squeezing action can be regulated so that it will producean irregular and haphazard tearing or laceration of the web withoutimpairing the transverse continuity of the web. These lacerations arediagrammatically represented in FIGS. 1, 6 and 7 by the referencenumerals 20. The minute corrugations are roughly indicated at 21 in FIG.7.

A further feature of the invention, contributing in large measure to theachievement of an enhanced fiber separation and exposure, withconsequent improved filtering qualities, lies in the creation oftransverse crimps or crinkles in the web it prior to its subjection tothe corrugating and mutilating action of the rollers 11. Thesetransverse crepes are'intended to be represented in a diagrammaticfashion at 22 in FIGS. 4 and 5. This creping'may be achieved in anywell-known fashion, not necessarily by apparatus forming part of thepresent improved device. It has been found that paper which has beentransversely creped lends itself unusually well to the stretching,grooving and lacerating action of the rollers 11; and that the combinedeffect of transverse crinkles at the start, and longitudinalcorrugations and lacerations superimposed thereon, produces a desirablefiber separation and exposure of unusual effectiveness from a filteringstandpoint. Moreover, the inherent longitudinal stretchability oftransversely-creped paper makes the action of the mutilating rollersmore controllable, so that desirably uniform results can be achieved incarrying out the procedure on a commercial scale.

A further feature of the invention is represented by the roller 13,which has a specially grooved surface configuration. As will be noted,the surface of this roller is provided with oppositely angled groovingsof a spiral character, extending in opposite directions from the centerof the roller. These groovings are of such character as to exert africtional force upon the web passing around the roller 13, this forceinitiating the convergence of the web toward a compacted formation, asindicated at 14.

In connection with the groovings referred to, it may be noted (merely byway of example) that a spiralling of roughly three complete turns perinch of longitudinal length of the roller is adequate for the purpose,and that grooves having flat bottoms and a depth of as little as of aninch have proven to be satisfactory. The grooves may be /8 of an inch inwidth, and the ridges between them (also having flat top surfaces) maybe approximately of an inch wide. The important feature of theconfiguration is, of course, the opposite inclinations of the spirals,outwardly from the center of the roller, whereby the mutilatedcorrugated web is frictionally urged toward a converging path of travelas it changes its direction in passing around the guide roller. Theroller surface is preferably of brass, and if desired the entire roller13 may 'be formed of an element of suitably machined brass tubing.

The filters produced by the described process and structure areunusually uniform, and the filtering action is highly efiective withoutretarding the draft through the cigarette of which the filter forms apart. This desirable result is achieved, in part, by the improvedprocedure herein described, and the special manner in which the web offibrous material is lacerated and distorted to disarrange and displaceits fibers.

While only a single embodiment of the invention has been illustrated anddescribed, it is obvious that the invention is not to be restrictedthereto, but is broad enough to cover all structures and procedureswhich fall within the scope of the appended claims.

What is claimed is:

1. In an apparatus for conditioning a fibrous Web to separate its fiberswithout destroying the transverse continuity of the web, a pair ofmutilating rollers mounted for rotation on parallel adjacent axes, saidrollers having each the same circumferentially grooved configurationdefining closely spaced alternate ridges and valleys, said rollers beingarranged in nested proximity with the ridges of each roller extendinginto the valleys of the other, each ridge having a cross-sectionalcontour which exposes at least one sharp edge, each valley having across-sectional contour which presents a relatively fiat surface inopposition to each ridge edge, the perpendicular distance from saidrelatively fiat surface to said ridge edge being smaller than the axialdistance between adjacent ridges of said nested rollers, and means forpassing the web to be treated between said rollers, whereby the webbecomes irregularly torn along the regions constrained to squeezebetween the sharp ridge edges and the relatively flat surfaces opposedthereto.

2. In an apparatus for conditioning a fibrous web to separate its fiberswithout destroying the transverse continuity of the Web, a pair ofmutilating rollers mounted for rotation on parallel adjacent axes, saidrollers having each the same circumferentially grooved configurationdefining closely spaced alternate ridges and valleys, said rollers beingarranged in nested proximity with the ridges of each roller extendinginto the valleys of the other, each ridge having a flat outer face andsharp lateral edges, each valley having a cross-sectional contour whichpresents a relatively flat surface in opposition to each ridge edge, theperpendicular distance from said relatively fiat surface to said ridgeedge being smaller than the axial distance between adjacent ridges ofsaid nested rollers, and means for passing the web to be treated betweensaid rollers, whereby the web becomes irregularly torn along the regionsconstrained to squeeze between the sharp ridge edges and the relativelyflat surfaces opposed thereto.

3. In an apparatus for conditioning a fibrous web to separate its fiberswithout destroying the transverse continuity of the web, a pair ofmutilating rollers mounted for rotation on parallel adjacent axes, saidrollers having each the same circumferentially grooved configurationdefining closely spaced alternate ridges and valleys, said rollers beingarranged in nested proximity with the ridges of each roller extendinginto the valleys of the other, each ridge having a fiat outer face andsharp lateral edges, each valley having a smoothly curved concavecrosssectional contour which presents a relatively fiat surface inopposition to each ridge edge, the perpendicular distance from saidrelatively fiat surface to said ridge edge being smaller than the axialdistance between adjacent ridges of said nested rollers, and means forpassing the web to be treated between said rollers, whereby the webbecomes irregularly torn along the regions constrained to squeezebetween the sharp ridge edges and the relatively fiat surfaces opposedthereto,

4. In an apparatus of the character described, a pair of mutilatingelements mounted for rotation on parallel adjacent axes, means forpassing a fibrous web between said elements, said elements being adaptedto separate some of the fibers of said web without destroying thetransverse continuity of the web, and means for initiating convergenceof said mutilated Web toward a compacted formation, said meanscomprising a roller positioned to guide the mutilated web through asharp change of direction, said roller having a grooved surfaceconfiguration 5 which includes oppositely angled spiral groovingsextending in opposite directions from the center of said roller and saidroller being so rotated that it exerts frictional forces upon the web indirections toward the center of said roller thereby tending to reducethe Width of said 10 web.

References Cited in the file of this patent UNITED STATES PATENTS HatterMar. 4, 1924 Greis Dec. 1, 1925 Cannard Sept. 22, 1931 Antonsen Dec. 17,1933 Cumfer Oct. 17, 1939 Marogg Sept. 2, 1958

